Grinding and polishing machine



Nov. 6,, 1962 w. H. BANTA, sR 3,061,981

GRINDING AND POLISHING MACHINE Filed March 3, 1961 3 Sheets-Sheet 1 INVENTOR.

WESLEY H. BA-TA2 ATTORNEYS.

Nov. 6., 1962 w. H. BANTA, SR I $661,981

' GRINDING AND POLISHING MACHINE Filed March 3. 1961 3 Sheets-Sheet 3 INVENTOR. WESLEY H.BAN-rA,Se, BY

3,061,981 GRINDING AND POLISHING MAC Wesley H. Banta, Sr., Box 158, North Bend, Wash. Filed Mar. 3, 1961, Ser. No. 93,183 11 Claims. (Cl. 51119) This invention relates to improvements in grinding and polishing apparatus, and more particularly to a novel machine for flat-grinding and polishing gem stones, and other precious and semi-precious materials, such as petrified wood and the like.

The primary object of the invention is the provision of a generally improved and more efficient machine of the kind indicated which grinds and polishes more quickly and produces more satisfactory work in less time and at less expense than existing machines in its category, utilizing a reciprocating plate.

Another object of the invention is the provision of a machine of the character indicated above wherein the grinding and polishing plate is circular, rather than square or polygonal, whereby the entire surface of the plate is available for grinding and polishing, and undesirable accumulations of abrasive grits in corners is eliminated, whereby more eificient and uniform grinding and polish ing action is obtained, with less waste of abrasive material and need for regrinding.

A further object of the invention is the provision, in a machine of the character indicated above, of a circular plate whose grinding and polishing surface is formed with a spiral groove, leading outwardly from its center to its periphery, which moves to feed abrasive grits outwardly from the center of the plate to the periphery of the plate, so as to be available to become spread evenly over the entire surface of the plate, and to be returned from the periphery of the plate toward the center of the plate, by the oscillation of the plate, so as to avoid accumulations of abrasive material at the periphery of the plate and enhance the uniform distribution of abrasive material over the surface of the plate.

A still further object of the invention is the provision of a grinding and polishing plate of the character indicated above, whichis desired to be quickly and easily removed from the machine for washing and other purposes, and replaced in the machine so as to eliminate substantial loss of time in grinding and polishing operations in the cleaning of the plate.

Yet another object of the invention is the provision of a plate of the character indicated above wherein the plate is provided with an upstanding peripheral wall which serves to confine abrasives and other material to the surface of the plate and prevent its falling off the plate into the interior orupon the exterior of the machine, and a resilient bumper at the inner side of the peripheral wall which prevents injurious and noisy contact of objects being ground and polished on the surface of the plate, with the peripheral wall. V 7

Still another object of the invention is the provision of a safer and quicker opearting machine of the character indicated above, wherein all moving parts are protectively enclosed and areout of harms reach of children, pets, and inexperienced adults, and access of outside dirt to the working parts of the machine is reduced to a minimum. Other important objects and advantageous features of the invention 'will be apparent from the following description and the accompanying drawings, wherein, for purposes of illustration only, a specific form of the invention is set forth in detail.

In the drawings: FIGURE 1 is a perspective view of a machine of the present invention;

FIGURE 2 is an enlarged top plan view of said machine, parts beneath the grinding and polishing plate being shown in phantom lines;

FIGURE 3 is a further enlarged vertical transverse section taken on the line 33 of FIGURE 1;

FIGURES 4 and 5 are horizontal sections taken on the lines 44 and 55, respectively, of FIGURE 3;

FIGURE 6 is a still further enlarged, fragmentary vertical transverse section taken on the line 66 of FIGURE 5; and

FIGURE 7 is a fragmentary horizontal section taken on the line 77 of FIGURE 6.

Referring in detail to the drawings, wherein like numerals designate like parts throughout the several views, the illustrated machine comprises an open-ended vertical cylindrical casing 10 having a free upper edge 12 and a free lower edge 14. Seated and secured to the lower end of the casing 10 is a lower spider '16, which is preferably in the form of a solid aluminum casting comprising a flat hub 18, radial arms 20, and a flat rim 22. The rim 22 is provided, in its upper side, with a peripheral groove 24, in which the lower edge 14 of the casing 10 seats and is secured, as by a press fit. The spider 16 is levelled relative to and supported on a supporting surface, by means of vertically adjustable feet 26, equally spaced around the rim 22, and preferably comprising vertical screws 28 threaded through the rim and having enlarged surface-engaging discs 30, on their lower ends. Lock nuts 32 are threaded on the screws against the upper surface of the rim 22, for locking the screws relative to the rim, after the machine has been levelled on a supporting surface. 7

The hub 18 015 the lower spider 16 is formed, in its upper surface, with a central depression which includes a central cylindrical portion34 and a beveled larger diameter portion 36, at the upper end of the portion 34 which defines a seat. A self-centering ball bearing 38, of the same type as those shown in FIGURE 6, is supported upon the hub 18, and comprises a pair of registered lateral annular flanges 40 on an annular housing 42, to which the periphery of an outer ball race 44 is secured. The outer race 44 is formed with a compound annular inner face which is composed of a groove 46, opening to the bottom of the race 44, which merges, at its top, into an annular concave groove 48, the grooves 46 and 48 being about half the width of the diameter of ball bearings 50 engaged therein. The bearing 38 further comprises an inner race 52 having a central shaft receiving opening 54 and an outer face which is composed of a groove 56, opening to thetop of the race 52 and merging, at its bottom, into an annular concave groove 58, the grooves 56 and 58 being about half the width of the diameterof theball bearings 50, and the races 44 and 52 being connected togethed by the ball bearings 50. The flanges 40 rest upon the upper surface of the spider hub 18, with the bottoms of the outer race 44 and the bottom of the housing 42 positioned in the 'hub recess and resting upon the seat 36 with spaced bolts 59 extending through the flanges and the hub. The lower end of a perpendicular shaft 60 is engaged through the bearing 38 and has a thrust collar 39 resting thereon.

The machine further comprises an upper spider 62, gen erally similar to the lower spider 16, but provided with a central shaft-receiving opening 64 in its hub 18', and preferably having three, instead of four arms 20', and having threaded through its rim 22, at ninety degrees apart, vertical screws 66, having enlarged diameter bearing discs 68 on their upper ends. Lock nuts 70 are threaded on the screws 66 against the upper surface of the rim 22. The bearing discs 68 threadably and supportably engage the flat and smooth undersurface 72 of a circular grinding and polishing plate 74, at locations near its peripheral edge 76.

The plate 74 is preferably a solid machined aluminum casting of substantial thickness, which is preferably of about the same outside diameter as the casing 10, and has a downwardly extending central boss 78 which is formed, in its lower end, with a concentric socket 80, which receives a half-cylindrical eccentric 82, on the upper end of the shaft 60.

The shaft 60 extends freely through the hub opening 64, and through an intermediate self-centering bearing 84, similar to the lower spider bearing 38, but mounted to the underside of the hub 18.

The eccentric 82 is engaged through an upper selfcentering bearing 86, similar to the bearings 38 and 34, and mounted to the lower end of the boss 78, by means of studs 88 threaded thereinto. The related portions of the shaft 60, engaged through the intermediate and lower bearings, are secured, in suitable manner, to the inner races of the bearings, while the eccentric 82 is freely engaged in the upper hearing.

The grinding and polishing plate 74 has an upstanding peripheral retaining wall 90 which serves to confine abrasive material, such as wet grits, on the upper or grinding and polishing surface 92 of the plate 74. The plate 74 is held down in place upon the bearing discs 68 by vertical contractile coil springs 94 which are stretched between hooks 96 on the outer ends of apertured plates 98, which are circumposed upon the screws 66, beneath the lock nuts 70, and inturned hooks 100 on the lower ends of clips 102. The clips 102 are inverted L-shaped straps having standard portions 104 which bear against the peripheral edge of the plate 74, and foot portions 106 which bear upon the upper edge of the peripheral wall. The foot portions 106 terminate in downwardly extending hooks 108 which bear against the inner surface of the wall 90, and are spaced upwardly from the upper surface 92 of the plate 74. A preferably plastic material bumper ring 110 is supported in the hooks 108 around and against the inner surface of the wall 90. Removing the plate 74, for cleaning or other purposes, involves merely disconnecting the springs 94, from the lower hooks 96 and lifting the plate 74 off the upper end of the shaft 60, and replacing the plate involves merely reseating the same on the bearing discs 68 and on the upper end of the shaft 60, and reconnecting the springs 94.

The upper surface 92 of the plate 74 is flat and smooth, except for a preferably V-shaped spiral groove 112 whose convolutions are uniformly and relatively widely spaced from each other, and which struts at the center of thei plate 74 and terminates, at its outer end, as indicated at 114, close to the peripheral wall.

Secured adjustably on the shaft 60 and spaced between the upper spider 62 and a pulley wheel 116, fixed on the shaft 60, is a counterweight 118, which comprises a circular block 120 which is formed with a diametrically elongated closed slot 122, having arcuate inner and outer ends 124 and 126, respectively, the same in diameter as the shaft 60. The slot 122, as shown in FIGURE 6, extends outwardly from the center of the block 120. A long set screw 128 is threaded diametrically through the block 120 and through the inner end 124 of the slot 122 to engage one side of the shaft 60, and a short set screw 130 is threaded diametrically through the block 120 and the outer end 126 of the slot, to engage the opposite side of the shaft 60. Lock nuts 132 on the screws are adapted to bear against the peripheral edge of the block 120. Because of the above described structural features, the counterweight 118 is capable of being positioned at any suitable balancing location on the shaft 60 and in any suitable position therearound, and is capable of being inverted on the shaft, to produce smooth and vibrationless operation of the shaft 60 and the plate 74. In this connection the yielding and retrieving characteristics of the springs 94 serve to reduce noise and vibration in the operation of the machine.

The machine is driven by an electric motor 132 having an upstanding vertical shaft 134 which is coupled to the pulley wheel 116 on the shaft 60 by a flexible belt 136. The motor 132 is fixed to one side of an upstanding plate 138 which rises from an upstanding bracket plate 140, on one of the arms 20 of the lower spider 16. The plate 140 has spaced horizontally elongated slots 142 which are traversed by studs 144 screwed into the lower part of the plate 138, and providing for tightening the belt 136. An insulated on-and-off switch 146 is mounted in an opening in the casing sidewall, and the electrical leads 148, to the motor and to the switch, are brought out of the casing through an insulating grommet 150 in an opening in the casing sidewall.

In operation, the motor 132 being in operation, the shaft is rotated on its axis and its eccentric 82 rotates in the upper bearing 86 whereby orbital movement of the plate 74 is produced. Rotation of the plate 74, relative to the shaft 60, and on the bearing discs 68, is limited by the restraining action of the springs 94. However, some vagrant and slight rotation of the plate takes place, because of the yielding character of the springs 94, which serves limited reciprocation of the plate, in a direction crosswise of the principal line of orbital movement of the plate. This limited crosswise orbital movement, in conjunction with the principal orbital movement of the plate 74, assists in distributing wet abrasive material, present on the surface 92 of the plate 74, and in the spiral groove 112, more uniformly over the surface 92, with resultant more uniform and finer polishing action.

Although there has been shown and described herein a preferred form of the invention, it is to be understood that the invention is not necessarily confined thereto, and that any change or changes in the structure of and in the relative arrangements of components thereof are contemplated as being within the scope of the invention as defined by the claims appended hereto.

What is claimed is:

1. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft.

2. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket,

'5 and motor means supported within the casing below said upper spider and operatively connected to said shaft, and rotatably and vertically adjustable counterweight means secured on said shaft below said upper spider.

3. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, and rotatably and vertically adjustable counterweight means secured on said shaft below said upper spider, said counterweight means comprising a block having an eccentric diametrical slot having inner and outer ends, the shaft extending through said slot and engaged with a slot end, and set screws threaded through the block against opposite sides of the shaft.

4. A grinding an polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, and rotatably and vertically adjustable counterweight means secured on said shaft below said upper spider, said counterweight means comprising a block having an eccentric diametrical slot having inner and outer ends, the shaft extending through said slot and engaged with a slot end, and set screws threaded through the block against opposite sides of the shaft, said set screws entering the slot at the ends thereof.

5. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, said retaining means comprising vertical coil springs.

6. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket,

a Vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, said retaining means comprising vertical coil springs, and clips engaged over the peripheral edge of the plate, and springs being secured, at their upper ends to the clips, said hooks on the upper spider with which the lower ends of the springs are receivably engaged.

7. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, said retaining means comprising vertical coil springs, and clips engaged over the peripheral edge of the plate, and springs being secured, at their upper ends to the clips, said hooks on the upper spider with which the lower ends of the springs are receivably engaged, said plate having an upstanding peripheral wall over which the clips are engaged.

8. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, vertically adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, said retaining means comprising vertical coil springs, and clips engaged over the peripheral edge of the plate, and springs being secured, at their upper ends to the clips, said hooks on the upper spider with which the lower ends of the springs are receivably engaged, said plate having an upstanding peripheral wall over which the clips are engaged, said clips having depending hooks at the inner side of said wall, and a plastic bumper ring engaged with the inner side of the wall and engaged in said depending hooks.

9. A grinding and polishing machine comprising a vertical cylindrical open-ended casing having upper and lower edges, upper and lower spiders severally secured in the upper and lower ends of the casing, depending vertically adjustable feet on said lower spider, said spiders having hubs and rims, verticaly adjustable screws threaded through and upstanding from the upper spider and spaced therearound, bearing discs on the upper ends of said screws above the upper spider, a circular grinding and polishing plate seating slidably upon said bearing discs, said plate having a peripheral edge, resilient retaining means acting between the plate and said upper spider and holding the plate yieldably in registration with the upper end of the casing, said plate having an eccentric socket, a vertical shaft journalled in said casing, an eccentric on the upper end of said shaft rotatably engaged in said socket, and motor means supported within the casing below said upper spider and operatively connected to said shaft, and rotatably and vertically adjustable counterweight means secured on said shaft below said upper spider, said lower spider hub having self-centering bearing means journalling the lower end of the shaft, said upper spider hole having an opening passing the shaft and a self-centering bearing through which the shaft passes, said plate having a self-centering bearing on its undersurface and registered with the socket, through which the shaft is journalled.

10. A grinding and polishing machine comprising a vertical open-ended casing, an upper spider secured in the upper end of said casing, vertically-adjustable screws threaded through and upstanding from said spider and spaced therearound, bearing discs on the upper ends of said screws above said spider, a grinding and polishing plate seating slidably upon said bearing discs, resilient means acting between said plate and said spider and holding said plate yieldably in registration with the upper end of said casing, and means operatively connected to said plate for imparting orbital movement to said plate.

11. A grinding and polishing machine comprising a vertical open-ended casing, an upper spider secured in the upper end of said casing, a lower spider secured in the lower end of said casing, depending vertically-adjustable feet on said lower spider, vertically-adjustable screws threaded through and upstanding from said upper spider and spaced therearound, bearing discs on the upper ends of said screws above said upper spider, a grinding and polishing plate seating slidably upon said bearing discs, resilient means acting between said plate and said upper spider and holding said plate yieldably in registration with the upper end of said casing, and means operatively connected to said plate for imparting orbital movement to said plate.

References Cited in the file of this patent UNITED STATES PATENTS 983,517 Ratclifie Feb. 7, 1911 1,960,447 Metrick May 29, 1934 2,145,888 Moulton et al Feb. 7, 1939 2,320,376 Mueller June 1, 1943 2,440,931 Casson May 4, 1948 2,466,516 Van Den Hove Apr. 5, 1949 2,807,918 Rupp Oct. 1, 1957 2,922,264 Mushrush Jan. 26, 1960 2,949,908 McElroy Aug. 23, 1960 

